Former Wayne State University opthalmology researchers Raymond Iezzi and Rangaramanujam Kannan have developed a new way to treat age-related macular degeneration and retinitis pigmentosa using injections of nanoparticles, the university announced earlier this month. Iezzi, who has since gone on to the Mayo Clinic, and Kannan, who is now with Johns Hopkins, are currently in the process of seeking patents for their groundbreaking treatment.
According to the National Institutes of Health, macular degeneration is the main cause of vision loss in older Americans, affecting more than 7 million people, while retinitis pigmentosa impacts an estimated 1 in 4,000 people nationally. There is no cure, so an effective treatment has the potential to help hundreds of millions patients across the globe.
Kannan says he and Iezzi began researching ways to treat macular degeneration after an ophthalmologist colleage mentioned that if he had a simple injection capable of treating the disease for even a month, he’d have a line of interested patients stretching around the block. Currently, doctors inject a small pellet into a patient’s eyeball containing a drug to treat the disease. This method leaves a lot to be desired, Kannan says, because it causes side effects, not the least of which is a 5 millimeter object floating around the eye.
“Treating the disease at the back of the eyeball was a problem, and treating the disease without side effects was a problem,” Kannan says. “But even before these problems are created, there’s the problem of neuroinflammation, which causes cells in the retina to go rogue.”
Kannan and Iezzi turned their attention to dendrimers, tree-like, non-cytotoxic nanoparticles that act as polymeric drug-delivery vehicles. They injected dendrimers attached to a steroid medication into the eyes of rats. The drug “walked right through” the eyes of healthy rats, but when injected into the eyes of rats with degeneration, the drug delivery system activated microglial cells, the immune cells tasked with cleaning up dead and dying material in the eye. Kannan says he and Iezzi were surprised to learn that the activated microglia in the degenerating retina appeared to eat the dendrimers selectively and retain them for at least a month.
“The idea is, the cells that cause problems consume poison and shut down,” Kannan says. “As little as .1 micrograms is effective for an entire month.”
Kannan didn’t expect the treatment to last longer than a month, but he and Iezzi’s research found that it did. The current formulation works for a few months with no side effects. Now the pair are working on adding compounds to the original formulation to see if the treatment effect can last even longer. Kannan says all of the research thus far has been conducted at Wayne State.
“There’s quite a bit of interest in this technology,” he adds. “It’s a very simple construct and an interesting way to use nanotechnology to target the disease process. Though there’s been a lot of work using nanotechnology in cancer-treatment applications, this is among the first for diseases involving neural degeneration.”
Kannan’s wife is a member of Wayne State’s medical school faculty, and he recently collaborated with her to prove that this same treatment approach works in degenerative brain diseases such as cerebral palsy. He’s seeking a patent for that too, though he expects the retinal application will be the first one commercialized.
